How to troubleshoot when the air conditioning compressor trips?

When we plugged the power plug of the air conditioner into the power socket, the air switch immediately tripped! This inevitably raises doubts: Is it because the compressor is leaking electricity? Don't panic, by following the following five steps, we can accurately confirm the compressor leakage fault.

Step 1: Measure the resistance between the power plug N and the ground
Just as the air conditioner plug is plugged into the power outlet, the air switch quickly trips for protection. At this point, we need to determine whether there is a malfunction in the air conditioner itself or a problem with the air switch. At this point, the multimeter came in handy. Use the resistance block of the multimeter and connect the probes to the N and ground terminals of the power plug. Under normal circumstances, the resistance between these two should be infinite because there should be no conductive path between them. However, when we conducted actual measurements, we found that the resistance was about 100 ohms, which clearly indicates that there is a leakage fault in the air conditioner.

Step 2: Disconnect the outdoor unit terminal connection wire
Common leakage faults in air conditioners are found in outdoor units. To determine whether the fault is with the outdoor unit or the indoor unit, remove the four connecting wires except for the ground wire from the outdoor unit terminal. Use a multimeter resistor block, connect one probe to the N terminal of the terminal and the other probe to the ground terminal fixing screw. The measured resistance value is still about 100, thus determining that the fault is with the outdoor unit.

Step 3: Measure the resistance of the compressor lead to ground
The common leakage fault of outdoor units is in the compressor. Unplug the three leads of the compressor coil, totaling four plugs (with the blue wire at the N end connected in parallel with the blue wire of the running winding). Use a multimeter to measure the resistance between the common terminal black wire and ground (connected to a four-way valve copper tube). The normal resistance should be infinite, but the measured resistance is still 0.1350, indicating that the leakage fault is caused by the compressor.

Step 4: Measure the resistance between the compressor terminal and the ground
The melting of the insulation layer of the compressor lead and ground short circuit can also cause power on tripping faults. Remove the compressor wiring cover, check that the compressor leads are normal, unplug the connector plug on the compressor wiring terminal, and use a multimeter to measure the resistance between the common terminal (c) of the wiring terminal and the ground (connected to the compressor exhaust pipe). The measured value is 13.50, which confirms that the internal coil of the compressor is short circuited to ground and damaged.

Step 5: Troubleshooting method without multimeter
If there is no multimeter available for on-site maintenance, or if the multimeter is damaged and unusable, we can also use troubleshooting methods to repair the fault in this case. The specific steps are as follows:
Disconnect the 4 connecting wires at the outdoor unit terminal and perform insulation treatment, then power on and test the machine again. If the air switch no longer trips, it indicates that the fault is in the outdoor unit.
Restore the 4 connecting wires on the outdoor unit terminal block, then remove the 4 plugs of the 3 leads of the compressor in the electrical control box, and power on the machine again for testing. If the air switch no longer trips, it indicates that the fault is in the compressor.
Restore the 4 plugs of the 3 leads of the compressor in the electrical control box, remove the 3 lead plugs from the compressor terminal block, and finally power on the machine again for testing. If the air switch no longer trips, it can be determined that the compressor is damaged.

Summary: If the air conditioner trips after being powered on or turned on due to a leakage fault, it is usually caused by a short circuit of the compressor coil to ground. Of course, other situations such as short circuits or insulation layer detachment between indoor and outdoor unit connecting wires, melting of compressor lead insulation layer and ground short circuit, damage to air switch, etc. may also cause tripping, but the proportion is relatively small.

Shanghai KUB Refrigeration Equipment Co., Ltd.

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